1. Field of the Invention
The invention relates to a printing apparatus, and more particularly, to a three-dimensional printing apparatus.
2. Description of Related Art
With the increasing development of technology, many different technologies of constituting models layer by layer, such as additive manufacturing technology, are currently used for building physical three-dimensional (3-D) models. Generally, the additive manufacturing technology is to transform design information of 3-D model constituted by software, such as computer-aided design (CAD) software or the like, into a plurality of thin (quasi-two-dimensional) cross-sectional layers which are built on one another in succession. At the same time, a number of known techniques for forming the thin cross-sectional layers have been proposed. For instance, a printing module of a printing apparatus can usually be moved above a base along an XY-plane by reference to an XYZ-coordinate constructed from the virtual design data of 3D models, so as to extrude or deposit material in correct shape of the cross-sectional layer. The deposited material may then harden naturally or be cured by, for example, powerful light source, to form the desired cross-sectional layer. Therefore, by moving the printing module along a Z-axis layer by layer, a plurality of cross-sectional layers may gradually be stacked along the Z-axis, thereby enabling the deposit material to form a three-dimensional object in a layer by layer curing manner.
Taking for example the technique of forming the three-dimensional object by using a light source to cure the deposit material, the printing module is adapted to immerse into a liquid forming material filled within a tank, and the light source on a XY-plane irradiates the liquid forming material (viz. the deposit material), so that the liquid forming material can be cured and stacked on a moving platform of the printing module. As such, by moving the moving platform of the printing module along the Z-axis layer by layer, the liquid forming material may layer by layer be cured and stacked to form the three-dimensional object. In the process of forming the three-dimensional object through layer by layer stacking, if the three-dimensional object contacts the bottom of the tank following the movement of the moving platform, then the formed three-dimensional object is likely to be damaged due to contacting the bottom of the tank. In addition, if the cured liquid forming material adheres on the bottom of the tank, then the irradiation of the light source may likely to be affected and thereby influences the subsequent forming results. Therefore, under the current three-dimensional printing technique, how to provide the three-dimensional object obtained through three-dimensional printing with favorable printing quality has gradually become a focus of attention for the developers in the field.